Enhanced Grain Refinement and Porosity Control of the Polycrystalline Superalloy by a Modified Thermally Controlled Solidification

Jie, Ziqi; Zhang, Jun; Huang, Taiwen; Su, Haijun; Li, Yafeng; Liu, Lin; Yang, Wenchao; Fu, Hengzhi

doi:10.1002/adem.201600320

Cited by 11 publications

(5 citation statements)

References 19 publications

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“…During solidification, an increase in the shell temperature leads to a decrease in the cooling rate of the alloy liquid and a decrease in the nucleation ability of the shell surface, resulting in a decrease in the nucleation rate, a larger grain size, and a decrease in the number of grains. The higher shell temperature causes a difference in the cooling rate between the casting surface and the centre of the casting, which may result in the formation of columnar crystals that grow from the outside to the inside [10]. In addition, the increase in the shell temperature will make the grains coarser and the tissue uniformity worse.…”

Section: Resultsmentioning

confidence: 99%

“…The thermal control method is a fine-grained casting process that increases the cooling rate during the solidification of the casting by controlling the withdrawal rate, pouring temperature, shell temperature, and other process parameters, thus increasing the undercooling degree to raise the nucleation rate [3][4]. As the G/R ratio at the solid/liquid interface front in the thermal control solidification process must be tightly controlled within the equiaxed crystal region, the control requirement of the solidification process is much more demanding than that of directional and single crystal casting technology [5].…”

Section: Introductionmentioning

confidence: 99%

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Effect of shell temperature in thermal control solidification process on microstructure and stress rupture property of cast equiaxed superalloy

Cao

Shen

Li³

et al. 2023

22nd International Scientific Conference Engineering for Rural Development Proceedings

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Cast equiaxed superalloy is commonly used in the manufacture of engine turbine blades and complex structural castings due to its excellent casting properties and comprehensive mechanical properties. The more adaptable thermal control solidification process is usually used to refine the equiaxed crystal structure. In this paper, the microstructure and fracture surface of this alloy after solid solution were observed and characterized by means of OM, SEM, and EDS, and the effects of thermally controlled solidification processes with different shell temperatures on the microstructure and stress fracture properties of this alloy were investigated. The results showed that in this cast equiaxed crystal alloy, increasing the shell temperature from 1300 °C to 1330 °C causes the grain size to grow, microporosity to significantly decrease, and eutectic content and size to slightly increase. Both S1 and S2 alloys formed MC and M6C carbides after solid solution treatment. The size and content of carbides increased as the shell temperature rose, whereas the size and content of the γ’ phase decreased. As the shell temperature increases, the stress rupture properties increase slightly, while the degree of rafting increases dramatically. Cracks are mainly formed at the aggregation of microporosity, eutectics, and carbides. The reasons why cracks occur in the two alloys can differ. This study provides guidance for the design of a thermal control solidification process for cast equiaxed superalloys.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of shell temperature in thermal control solidification process on microstructure and stress rupture property of cast equiaxed superalloy

Cao

Shen

Li³

et al. 2023

22nd International Scientific Conference Engineering for Rural Development Proceedings

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show abstract

“…Zheng [6; 7] set the shell temperature in the solidliquid phase line temperature interval and improved the thermally controlled solidification process to reduce the shrinkage defects. Recently, Jie [8] used this technique to achieve a composite control of casting densities and grain size as a way to improve the performance of castings.…”

Section: Introductionmentioning

confidence: 99%

Effect of shell temperature on solidification organization of equiaxed crystal blade

Cao

Zhang

Li³

et al. 2023

22nd International Scientific Conference Engineering for Rural Development Proceedings

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The investigation was conducted into the effects of different shell preheating temperatures (1100 °C, 1150 °C, and 1180 °C) on the organization of solidification of isometric crystalline blades made for an aero-engine. The experimental results show that with the increase of shell temperature, the dendrite spacing and dendrite robustness gradually increase, while the area between dendrites gradually increases. The size of the eutectic gradually increases as the shell temperature rises, and there is no obvious regularity in the eutectic content. The size and content of carbide show a trend of decreasing first and then becoming larger, and the size relationship was 1180 °C > 1110 °C > 1150 °C. There is no obvious difference in the composition of carbides at different shell temperatures, all of them are MC-type carbides, and none of them decompose. At 1150 °C, γ΄ phase has a smaller size, the best cubical and most regular arrangement, while the largest size, worst cubicization and most irregular phase at 1180 °C.

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“…Formation of micro defects during solidification processes has gained the attention of many researchers since they affect the mechanical properties of solidified components [1][2][3]. Numerous attempts have been made to minimize porosity in castings [4][5][6]. For example, understanding bubble formation and motion during dendritic solidification would help to improve the quality of cast products [7].…”

Section: Introductionmentioning

confidence: 99%

A Comparative Study of Multiphase Lattice Boltzmann Methods for Bubble-Dendrite Interaction during Solidification of Alloys

2018

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This paper presents a comparative study between the pseudopotential Shan-Chen model and the phase field multiphase lattice Boltzmann method for simulating bubble dynamics during dendritic solidification of binary alloys. The Shan-Chen method is an efficient lattice Boltzmann multiphase method despite having some limitations, including the generation of large spurious currents. The phase field model solves the Cahn-Hilliard equation in addition to the Navier-Stokes equation to track the interface between phases. The phase field method is more accurate than the Shan-Chen model for simulation of fluids with a high-density ratio since it generates an acceptable small spurious current, though at the expense of higher computational costs. For the simulations in this article, the multiphase lattice Boltzmann model was coupled with the cellular automata and finite difference methods to solve temperature and concentration fields. The simulated results were presented and compared regarding the ability of each model to simulate phenomena at a microscale resolution, such as Marangoni convection, the magnitude of spurious current, and the computational costs. It is shown that although Shan-Chen methods can replicate some qualitative features of bubble-dendrite interaction, the generated spurious current is unacceptably large, particularly for practical values of the density ratio between fluid and gas phases. This occurs even after implementation of several enhancements to the original Shan-Chen method. This serious limitation makes the Shan-Chen models unsuitable to simulate fluid flow phenomena, such as Marangoni convection, because the large spurious currents mask completely the physical flow.

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Enhanced Grain Refinement and Porosity Control of the Polycrystalline Superalloy by a Modified Thermally Controlled Solidification

Cited by 11 publications

References 19 publications

Effect of shell temperature in thermal control solidification process on microstructure and stress rupture property of cast equiaxed superalloy

Effect of shell temperature in thermal control solidification process on microstructure and stress rupture property of cast equiaxed superalloy

Effect of shell temperature on solidification organization of equiaxed crystal blade

A Comparative Study of Multiphase Lattice Boltzmann Methods for Bubble-Dendrite Interaction during Solidification of Alloys

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